A communication system employed during wellbore operations, such as during drilling, cementing, fracturing, or other wellbore operations, which utilizes ultrasound (i.e., acoustic waves characterized by ultrasonic frequencies) to communicate sensor and/or control information from inside a riser and/or blowout preventer (BOP) to outside the riser/BOP, and/or vice versa. More specifically, the communication system may include an internal ultrasonic module (IUM) residing inside the riser/BOP and acoustically coupled to a drill string and/or a centralizer also inside the riser/BOP. The communication system may further include an external ultrasonic module (EUM) residing outside the riser/BOP and acoustically coupled to the riser/BOP. The ultrasound may traverse from the IUM to the EUM, and vice versa, using a communication path that may include propagation of the ultrasound through the drill string, the centralizer, and the riser/BOP without traversal through fluids contained within a fluid column enclosed by the riser/BOP.

A communication system employed during wellbore operations, such as during drilling, cementing, fracturing, or other wellbore operations, which utilizes ultrasound (i.e., acoustic waves characterized by ultrasonic frequencies) to communicate sensor and/or control information from inside a riser and/or blowout preventer (BOP) to outside the riser/BOP, and/or vice versa. More specifically, the communication system may include an internal ultrasonic module (IUM) residing inside the riser/BOP and acoustically coupled to a drill string and/or a centralizer also inside the riser/BOP. The communication system may further include an external ultrasonic module (EUM) residing outside the riser/BOP and acoustically coupled to the riser/BOP. The ultrasound may traverse from the IUM to the EUM, and vice versa, using a communication path that may include propagation of the ultrasound through the drill string, the centralizer, and the riser/BOP without traversal through fluids contained within a fluid column enclosed by the riser/BOP.

The disclosure relates to petroleum drilling, specifically a downhole signal receiving and transmitting device. The downhole signal receiving and transmitting device includes a receiving part, a control device, a mechanical assembly and a transmitting mechanism. The receiving part receives a signal transmitted by a lower end instrument, and the control device process the received signal, controls a motor to drive a rotating sleeve, and the mechanical assembly performs work. The mechanical assembly drives a mandrel to rotate a rotor continuously and regularly. When rotating, the flow area of the rotor and a stator changes to produce continuous pulses. The pressure waveform changes are monitored on the ground, and the measurement data are calculated by decoding. The device can obtain engineering parameters and geological parameters in the downhole drilling process in real time, which helps engineers to adjust the drilling trajectory and related parameters, and realize real-time measurement and control while drilling.

The disclosure relates to petroleum drilling, specifically a downhole signal receiving and transmitting device. The downhole signal receiving and transmitting device includes a receiving part, a control device, a mechanical assembly and a transmitting mechanism. The receiving part receives a signal transmitted by a lower end instrument, and the control device process the received signal, controls a motor to drive a rotating sleeve, and the mechanical assembly performs work. The mechanical assembly drives a mandrel to rotate a rotor continuously and regularly. When rotating, the flow area of the rotor and a stator changes to produce continuous pulses. The pressure waveform changes are monitored on the ground, and the measurement data are calculated by decoding. The device can obtain engineering parameters and geological parameters in the downhole drilling process in real time, which helps engineers to adjust the drilling trajectory and related parameters, and realize real-time measurement and control while drilling.

Methods and systems for generating pulses in drilling fluid are described. The methods include driving rotation of a rotor relative to a stator of a pulser assembly in an oscillatory manner. The oscillatory manner includes rotating an obstructing element from a middle position to a first blocking angle position and rotating the obstructing element from the first blocking angle position to a second blocking angle position such that selective obstruction occurs. Rotation of the at least one obstructing element selectively obstructs a stator flow passage when drilling fluid is flowing through the drill string to generate a pressure pulse in the drilling fluid and the oscillatory manner is an oscillation of the obstructing element between the first blocking angle position and the second blocking angle position such that a single oscillation is between two obstructed states of the stator flow passage.

Methods and systems for generating pulses in drilling fluid are described. The methods include driving rotation of a rotor relative to a stator of a pulser assembly in an oscillatory manner. The oscillatory manner includes rotating an obstructing element from a middle position to a first blocking angle position and rotating the obstructing element from the first blocking angle position to a second blocking angle position such that selective obstruction occurs. Rotation of the at least one obstructing element selectively obstructs a stator flow passage when drilling fluid is flowing through the drill string to generate a pressure pulse in the drilling fluid and the oscillatory manner is an oscillation of the obstructing element between the first blocking angle position and the second blocking angle position such that a single oscillation is between two obstructed states of the stator flow passage.

A downhole valve is described. The downhole valve has a pilot valve section and a tool section. The pilot valve section has a first tube. The tool section has a second tube slidably coupled to the first tube of the pilot valve section so as to provide fluid communication between the pilot valve section and the tool section. The tool section can be in the form of a signal valve section of a mud pulse telemetry valve, a reamer, a vertical steerable tool, a rotary steerable tool, a by-pass valve, a packer, a whipstock, or stabilizer.

A downhole valve is described. The downhole valve has a pilot valve section and a tool section. The pilot valve section has a first tube. The tool section has a second tube slidably coupled to the first tube of the pilot valve section so as to provide fluid communication between the pilot valve section and the tool section. The tool section can be in the form of a signal valve section of a mud pulse telemetry valve, a reamer, a vertical steerable tool, a rotary steerable tool, a by-pass valve, a packer, a whipstock, or stabilizer.

Methods and systems for characterizing fractures in a subterranean formation are provided. The method includes introducing an encapsulated explosive unit into a casing located in a wellbore within the subterranean formation and maintaining the encapsulated explosive unit in a stage of the casing. The method also includes detonating the encapsulated explosive unit within the stage to generate a pressure wave that passes through a group of perforations and into the fractures and measuring a reflected pressure wave using a pressure sensor coupled to the bridge plug to produce a pressure measurement. The method further includes converting the pressure measurement into an acoustic signal correlated with the pressure measurement by an acoustic signal generator contained in the bridge plug and transmitting the acoustic signal to apply acoustic pressure on a fiber optic cable coupled to an exterior surface of the casing.

Methods and systems for characterizing fractures in a subterranean formation are provided. The method includes introducing an encapsulated explosive unit into a casing located in a wellbore within the subterranean formation and maintaining the encapsulated explosive unit in a stage of the casing. The method also includes detonating the encapsulated explosive unit within the stage to generate a pressure wave that passes through a group of perforations and into the fractures and measuring a reflected pressure wave using a pressure sensor coupled to the bridge plug to produce a pressure measurement. The method further includes converting the pressure measurement into an acoustic signal correlated with the pressure measurement by an acoustic signal generator contained in the bridge plug and transmitting the acoustic signal to apply acoustic pressure on a fiber optic cable coupled to an exterior surface of the casing.